Fix for un-initialised buffer content when sending empty packets. Updated comments

diff --git a/include/lib/protocols/dtplug/defs.h b/include/lib/protocols/dtplug/defs.h
index 0b93aee..f0c8c20 100644 (file)
--- a/include/lib/protocols/dtplug/defs.h
+++ b/include/lib/protocols/dtplug/defs.h
@@ -43,7 +43,9 @@
  *
  * Sequence numbers, Quick data packets, data checksums and error codes
  *    The sequence number is on the 5 least significant bits of the sequence number field.
- *      this gives 64 sequence numbers which is more than enough.
+ *      this gives 31 sequence numbers which is more than enough.
+ *      A sequence number of 0 means "Out of band" data (usually unrequested data from slave
+ *      to master).
  *    When the most significant bit (bit 7) of the sequence number field (seq_num) is set
  *      in a request (master to slave), the slave MUST send an acknowledge packet or a reply
  *      with the same sequence number.
@@ -85,7 +87,7 @@ struct header {
        char start;    /* Start of paquet indicator */
        uint8_t type;  /* Packet type, used to provide information on the data structure */
        uint8_t checksum;  /* Header checksum */
-       uint8_t seq_num; /* Packet sequence number on bits 0:5, error indicator on bit 7 */
+       uint8_t seq_num; /* Packet sequence number on bits 0:4, error indicator on bit 7, quick data on bit 6 */
        union {
                struct data_information data;
                struct error_information err;
@@ -108,7 +110,7 @@ struct header {
 /* The following struct defines a generic packet.
  * Specific packets should be defined in specific structures.
  */
-#define PACKET_DATA_SIZE  64
+#define PACKET_DATA_SIZE  (64 - sizeof(struct header))
 struct packet {
        struct header info;  /* Packet header */
        uint8_t data[PACKET_DATA_SIZE];   /* packet data */

diff --git a/lib/protocols/dtplug/slave.c b/lib/protocols/dtplug/slave.c
index 859ee8e..48ea3c6 100644 (file)
--- a/lib/protocols/dtplug/slave.c
+++ b/lib/protocols/dtplug/slave.c
@@ -270,7 +270,7 @@ void dtplug_protocol_send_reply(struct dtplug_protocol_handle* handle,
                tx_info->seq_num = question->info.seq_num;
 
                len = sizeof(struct header); /* At least, send header on serial link */
-               if (error) {
+               if (error != NO_ERROR) {
                        tx_info->seq_num |= PACKET_IS_ERROR;
                        tx_info->err.error_code = error;
                        if (error == GOT_MANY_ERRORS) {
@@ -301,6 +301,9 @@ void dtplug_protocol_send_reply(struct dtplug_protocol_handle* handle,
                                        /* Update length of data to send on serial link */
                                        len += data_send_size;
                                }
+                       } else {
+                               tx_info->data.size = 0;
+                               tx_info->data.checksum = 0;
                        }
                }
 
@@ -338,7 +341,7 @@ void dtplug_protocol_send_reply(struct dtplug_protocol_handle* handle,
                if (data_sent < size) {
                        /* Move data pointer */
                        data_src += data_send_size;
-                       /* Update size to send. check against PACKET_DATA_SIZE is done at beginning of loop */
+                       /* Update size to send. Check against PACKET_DATA_SIZE is done at beginning of loop */
                        data_send_size = (size - data_sent);
                        /* Set packet type to continued data packet for following packets */
                        type = PKT_TYPE_CONTINUED_DATA;